Electrical switches with improved internal structure for grounding the contactor to the casing



. 3,329,778 AL STRU HE CASING July 4, 1967 M. F. BEDOCS ELECTRICAL SWITCHES WITH IMPROVED INTERN FOR GROUNDING THE CONTACTOR TO T Filed Nov. 8, 1965 //v vEA/me F ficdocs Miclzal 3,329,778 ELECTRICAL SWITCHES WITH IMPROVED IN- TERNAL STRUCTURE FOR GROUNDING THE CONTACTOR TO THE CASING Michael F. Bedocs, Wilmette, Ill., assiguor to Indak Manufacturing Corp., Northbrook, Ill., a corporation of Illinois Filed Nov. 8, 1965, Ser. No. 506,700 4 Claims. (Cl. 200-16) This invention relates to electrical switches.

One object of the present invention. is to provide new and improved electrical switches having internally grounded contactors.

Thus, it is an object of the present invention to provide an electrical switch which may be employed in a circuit which calls for the grounding of the contactor, without any need to provide a terminal, lead or other external means whereby the contactor will be grounded.

A further object is to provide a new and improved electrical switch having a contactor with spring means for slidably engaging the metal casing of the switch so as to ground the contactor to the casing.

Another object is to provide a switch of the foregoing character in which the contactor is formed with a pair of flanges having spring means thereon for engaging opposite walls of the metal casing.

A further object is to provide an electrical switch having internal means for reliably grounding the contactor to the casing, yet at extremely low cost.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view taken through an electrical switch to be described as an illustrative embodiment of the present invention.

FIG. 2 is a rear view of the switch with the terminal board removed, the view being taken generally as indicated by the line 2-2 in FIG. 1.

FIG. 3 is an elevational view looking at the front or inner side of the terminal board, the view being taken generally as indicated by the line 3-3 in FIG. 1.

FIG. 4 is a perspective view of the contactor for the switch in FIGS. 1-3.

FIG. 5 is a fragmentary view similar to FIG. 1, but showing a switch having a modified contactor.

FIG. 6 is a view similar to FIG. 2 but showing the modified switch of FIG. 5.

FIG. 7 is a perspective view showing the modified contactor employed in the switch of FIGS. 5 and 6.

3,329,778 Patented July 4, 1967 ice casing 12. It will be seen from FIG. 2 that the detent pr ojections 28 are arranged in two parallel rows on opposite sides of the slot 24. The effect of the detent projections 28 It will be seen that FIGS. 1-4 illustrate an electrical switch 10 which is particularly well adapted for use in automotive service. However, it will be understood that the switch may be employed for any other desired or suitable application. The illustrated switch 10 comprises a casing 12 which is made of metal and thus is electrically conductive. A carriage or slider 14 is movable with in the casing 12. In this instance, the slider 14 is adapted to be moved by means of an operating lever 16 which is pivoted on a bracket 18 secured to the front wall 20 of the casing 12. The lever 16 has an arm 22 which extends through a slot 24 in the casing 12 and is received in a slot or opening 26 formed in the slider 14. While the invention is being illustrated in connection with a lever-action switch, it will be understood that the invention is applicable to switches of other types.

By operating the lever 16, the slider or carriage 14 may be moved to a series of positions within the casing 12. A detent arrangement is provided to locate the carriage 14 in each of the positions of the switch. Thus, the front wall 20 of the casing 12 is formed with two sets of detent projections 28 which extend rearwardly into the is to form valleys or notches 30 therebetween. The carriage 14 is formed with detent projections 32 which are movable over the projections 28 and into the notches 30.

The switch 10 is provided with a movable contactor 34 and at least one fixed contact which is engageable by the contactor 34. In the present instance the switch 10 has three contacts 36, 37 and 38 which are engageable successively by the contactor 34. The contacts 36-38 are mounted on an insulating terminal board or plate 40 which is secured to the casing 12 so as to form the rear wall thereof. Terminal lugs or prongs 42, 43 and 44 are mounted on the insulating board 40 and are connected to the respective contacts 36, 37 and 38.

The illustrated contactor 34 is in the form of a metal member or plate which is mounted on the slider or carriage 14 and is movable with the carriage into engagement with the various contact points 36-38. The contactor 34 may be formed with a pair of forwardly projecting prongs or flanges 46 which are received in notches 48 formed in the carriage 14, so as to locate and retain the cont-actor on the carriage. A spring 50 is provided between the contactor 34 and the carriage 14 so as to press the contactor 34 rearwardly, while urging the carriage 14 forwardly. The illustrated spring 50 is of the coiled compression type, but various types of springs may be employed. The spring 50 provides contact pressure between the contactor 34 and the contacts 36-38, when the con-' :tactor is moved into engagement with the contacts. At the same time, the spring 50 provides biasing force between the detent projections 32 on the carriage 14 and the detent projections 28 and notches 30 on the casing 12..

In accordance with the present invention, the illustrated switch 10 is provided with means for internally grounding the contactor 34 to the casing 12. In the illustrated construction, the contactor 34 is formed with at least one flange 52 having means for slidably engaging a conductive member of the casing 12. Preferably, such means take the form of a spring member 54 on the flange 52. Actually, the illustrated contactor 34 has a pair of such flanges 52 with spring members 54 slidably engaging op posite side walls 56 of the casing 12. As shown in FIGS. 1-4, the spring members 54 are in the form of bowshaped spring portions arching outwardly from the flanges 52. It will be seen that the bow-shaped spring members 54 are formed from the central portions of the flanges 52. Cutouts 58 are formed in the flanges 52 to the rear of the bow-shaped spring members 54 so as to render them more flexible. The bow-shaped spring members 54 press outwardly against the 'side walls 56 of the casing 12.

It Will be understood that the spring members 54 engage the casing 12 at all positions of the contactor 34 so that the contactor is effectively grounded to the casing at all times. Thus, the switch is well adapted for use in circuits which call for the grounding of the contactor. A motor speed control circuit 60 of this type is illustrated diagrammatically in FIG. 1. The circuit is energized by a battery 62 having one side grounded. Thus, the grounded side of the battery is eifectively connected to the casing 12, which is also grounded. A motor 64 is connected between the ungrounded side of the battery and the terminal 44. The motor 64 may be adapted to operate a fan or the like. A current limiting resistor 66 is connected between the terminals 43 and 44, and another resistor 68 is connected between the terminals 42 and 43.

The switch 10 has an OFF position in which the contactor 34 does not engage any of the contact points 36-38. From the OFF position, the contactor 34 is movable to a position in which it engages the contact 36 and thereby completes an energizing circuit for the motor 64 3 through the resistors 66 and 68. It will be understood that the resistors limit the current through the motor and thus cause it to operate at low speed.

In the next position of the switch, the contactor 34 engages the contact 37 and thus completes an energizing circuit in which only the resistor 66 is in series with the motor 64. Thus, the motor 64 is operated at a medium speed.

Finally, the contactor 34 is engageable with the contact 38 so that the motor 64 is energized directly from the battery 62. With both of the resistors 66 and 68 out of the circuit, the motor 64 is operated a high speed.

In all of the positions of the switch, the contactor 34 is effectively grounded by the bow-shaped spring members 54. It is not necessary to provide any external means for grounding the contactor. Thus, the grounding of the contactor is brought about at extremely low cost.

FIGS. 7 illustrate a modified switch 70 which is the same as the switch of FIGS. 1-4, except that the switch 70 is provided with a contactor 72 of modified construction. The contactor 72 has locating prongs 46 the same as in the case of the contactor 34. However, the flanges 52 are replaced with modified means for grounding the contactor 72 to the casing 12. Such means comprise at least one flange 74 having a spring finger 76. Actually, the illustrated contactor 72 has two such flanges 74 with spring fingers 76 for engaging the opposite side walls 56 of the casing 12. It will be seen that the flanges 74 project forwardly from the contactor 72. The spring fingers 76 extend at right angles to the flanges 74 and in this case project upwardly. Contact points 78 are formed on the spring fingers 76 to engage the walls 56 of the casing 12. The spring fingers 76 provide a high degree of flexibility so that they insure the maintenance of good electrical contact with the walls of the casing. The spring fingers readily follow any slight irregularities in the casing walls.

It will be evident that the present invention provides eflicient and economical means for internally grounding the contactor of the switch. In this way, it is not necessary to go to the expense of providing external leads, terminals and other means for grounding the contactor.

Various other modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following claims.

I claim:

1. In an electrical switch,

the combination comprising a metal casing,

a contactor movable in said casing,

an insulating contact supporting member mounted on said casing,

a plurality of contacts mounted on said member and engageable by said contactor, and a contacting member mounted on said contactor and slidably engaging said casing for grounding said contactor to said casing.

2. In an electrical switch,

the combination comprising a metal casing having opposite side walls,

an insulating board mounted on said casing and extending between said side walls,

a plurality of contact points mounted on said board,

a contactor movably mounted in said casing into engagement with said contact points,

operating means for moving said contactor,

and a pair of oppositely disposed contact flanges on said contactor and slidably engaging said side walls of said casing for grounding said contactor to said casing.

3. In an electrical switch,

the combination comprising a metal casing having opposite side walls,

an insulating board mounted on said casing and extending between said side walls,

a plurality of contact points mounted on said board,

a contactor movably mounted in said casing into engagement with said contact points,

operating means for moving said contactor,

and a pair of oppositely disposed contact flanges on said contactor and slidably engaging said side walls of said casing for grounding said contactor to said casing,

each of said flanges having a bow spring portion resiliently engaging the corresponding side wall of said casing.

4. In an electrical switch,

the combination comprising a metal casing having opposite side walls,

an insulating board mounted on said casing and extending between said side walls,

a plurality of contact points mounted on said board,

a contactor movably mounted in said easing into engagement with said contact points,

operating means for moving said contactor,

and a pair of oppositely disposed contact flanges on said contactor and slidably engaging said side walls of said casing for grounding said contactor to said casing.

each of said flanges including a spring finger resiliently engaging the correspondingside wall member.

References Cited UNITED STATES PATENTS 2,598,671 6/1952 Boothby 200l53 X 2,852,662 9/1958 Garland 200- X 3,235,679 2/1966 Schaad et a1 20016 ROBERT K. SCHAEFER, Primary Examiner.

J. R. SCOTT, Assistant Examiner. 

1. IN AN ELECTRICAL SWITCH, THE COMBINATION COMPRISING A METAL CASING, A CONTACTOR MOVABLE IN SAID CASING, AN INSULATING CONTACT SUPPORTING MEMBER MOUNTED ON SAID CASING, A PLURALITY OF CONTACTS MOUNTED ON SAID MEMBER AND ENGAGEABLE BY SAID CONTACTOR, AND A CONTACTING MEMBER MOUNTED ON SAID CONTACTOR AND SLIDABLY ENGAGING SAID CASING FOR GROUNDING SAID CONTACTOR TO SAID CASING. 